Improvements in lead dropping pencils



Sept. 26, 1961 c. cHELAzzl IMPROVEMENTS IN LEAD DROPPING PENCILS Filed April 12, 1957 2 Sheets-Sheet l MVM Sept. 26, 1961 c. cHELAzzl IMPROVEMENTS 1N LEAD DROPPING PENCILS 2 Sheets-Sheet 2 Filed April l2, 1957 INVENTOR hr/lira aZeZZZ/l ATTORNEYS 1 BY m,

nited States The present invention pertains to draftsmens lead dropping pencils. Such pencils -are so-called owing to the fact that the lead drops down when lit is freed from the mechanism clamping it within the pencil.

One of the disadvantages of prior pencils of this sort is that in order to adjust the lead the draftsman has hitherto been required to shift his ngers in order to push a button on the top of the pencil or otherwise operate the adjusting mechanism. The present invention permits the draftsman to -adjust the lead without any need of shifting his fingers on the body of the pencil. This improvement is achieved in the present invention by devising the pencil so that by inserting the point ina gauge near at hand and pushing downwards the lead automatically adjusts itself to the length `determined beforehand by the gauge. Of course the pencil can also be arranged to operate in the customary manner by pushing on the top thereof with the thumb.

Accordingly the primary object of the present invention is the provision of a pencil, particularly yfor draftsmen, which permits the latter to make instant and exact adjustments of the lead without need to change the posi tion of his ngers upon the pencil.

The invention is illustrated merely by way of example, without lany limitation thereby being intended, in the annexed drawings, in which:

FIG. 1 is a sectional view through the axis ofthe pencil showing one embodiment of the invention and the position of the parts of the pencil in the midst of adjustment of the lead by insertion of the point of the pencil into the gauge, also shown in section;

FIG. 2 shows the position of the parts of the pencil upon the completion of the adjustment shown in FIG. l;

FIG. 3 is a sectional view along the axis of the pencil showing `a modification of the embodiment in FIGS. l and 2;

FIG. 3 FIG. 3;

FIG. 4 is also a sectional View of a further embodiment of the invention;

FIG. 4' is a cross-section taken along the line 4-4 of FIG. 4;

FIG. 5 is an axial section showing a por-tion of an additional modiiication of the invention;

FIG. 6 is a cross-section taken along line 6--6 or" FIG. 5;

FIG. 7 is an axial section of the entire embodiment of which a portion is shown in FIG. 5;

FIG. 8 is an enlarged view of a portion of FIG. 7; and

FIG. 9 is a cross-section taken along the line 9-9 of FIG. 8.

Referring first to the embodiment in FIGS. l and 2, the pencil is provided with an external body 2 of cylindrical shape, as in FIGS. l, 2, 3 and 3' or of polygonal shape -as in FIGS. 4-9. Through the center of body 2, and coaxial therewith, passes tube 3 which contains the lead 1 and the lower end of which is formed into lead gripping members 4. The other end of tube 3 is provided with button 5 and push button 7, both buttons 5 and 7 being secured to tube 3. Body 2 is provided with lug 8 between which and button 7 is positioned helical compression spring 6 acting therebetween.

The lower portion of body 2 is adapted to receive operating sleeve 9 which is axially slidable thereon. Sleeve is -a cross-section taken along the line 3-3' of ice 9 is Secured to tube 3 by pins 10 or other similar means which pass through small elongated slots 11 in body 2. Slots l11 are suiiciently long to permit body 2 on the one hand, and tube 3 and sleeve 9 on the other hand, to move slidably with regard to each other against spring 6.

Gripping members 4 secure the lead in tube 3 by virtue i of the tension exerted by spring 6 which forces gripping members 4 upon lead 1 by the action of the tapered lower ends 12 of body 2 upon the cam =faces of gripping members 4.

The `adjusting gauge 25 is of such size that lead 1 and gripping members 4 can be wholly inserted therein (FIGS. l and 2). Downward pressure of the Idraftsmans ngers upon sleeve 9 causes tube 3 and gripping members 4 to extend out from body 2, thus releasing lead 1 and permitting it to drop down a preselected distance in gauge 25. The extent of the insertion of gripping members 4 into gauge 25 is limited by cooperation between operating sleeve 9, the ends 12 of body 2 and gauge 25 so that the projection of lead 1 from gripping members 4 is always a constant amount. When the downward pressure of the draftsmans fingers is released, sleeve 9 and gripping members 4, by means of spring 6, return to their static position (FIG. 2), once again gripping the lead, whereupon the pencil upon removal from gauge 25 is ready for use. The entire operation can be performed very swiftly and accurately.

In the embodiment shown in FIG. 3, tube 3 is provided with a stop ring 15 secured thereto and the lower end 14 of body 2 is provided with clamping sleeve 13 threaded therein which acts upon the cam faces of gripping members 4. Helical compression spring 6 is positioned about tube 3 between stop ring 15 and clamping sleeve 12. The operation of this embodiment is exactly like that of the embodiment in FIGS. l and 2.

In the embodiment shown in FIG. 4 tube 3 is secured to body 2 by means of ring 16. Ring 15 functions to provide a thickness which permits to secure the small pins l10 to the inner tube 3 and, of course, said ring is integral with said tube 3. Ring 16 lfrictionally secures tube 3 to body 2 in any known way by soldering, threading, etc. Also secured to tube 3 is stop ring 15 and at the lower end of body 2 clamping sleeve 13 which is provided with tapered ends 12 is positioned between body 2 yand tube 3 lso that it is slideable along the latter and engageable with gripping members 4. Spring `6 is located around tube 3 between stop ring 15 and clamping sleeve 13. The operation of this embodiment yis very similar to that of FIGS. l and 2. Downward pressure of the draftsmans hands upon body 2 causes tube 3 to slide out from clamping sleeve 13, compressing spring 6 and thus releasing gripping members 4 and allowing the lead to drop.

The embodiment shown in FIGS. 5-9 permits a finer degree of control at the tip of the pencil by limiting the extent to which gripping members 4 can project from the end of clamping sleeve 13 and at the same time making adjustable the distance which sleeve 13, gripping members 4 and lead 1 project 'from body 20. This is accomplished by securing `a stop tube 17 within and to body 2 a distance behind the upper end of clamping sleeve 13. To tube 3 tube 18 is secured and is threaded within tube 19 `secured to body 2. By rotating body 2 relative to tube 3 the distance between the lower end of stop tube 17 and the upper end of clamping sleeve 13 can be varied. Such rotation of tube 3 is provided by cap 20 which is secured to tube 3 and -is moveable relative to and projects beyond body 2.

In order to prevent rotation of clamping sleeve 13 relan tive to body 2, when, for instance lead 1 is sharpened in a rotary Sharpener, and which by virtue of the force exerted by clamping sleeve 13 upon gripping members 4 would also rotate tube 3 and thus disturb the adjustment aiorded by tubes 18 `and 19, the lower end of body 2 is provided with axially parallel grooves 21 which are slideable in corresponding grooves in clamping sleeve 13.

The projection of the lead relative to body 2 is controlled merely by rotating tube 3 by means of cap 20 relative -to body 2 which results in a greater or a lesser emergence of clamping sleeve 13 and gripping members 4- from the lower end of body 2. Furthermore, inasmuch as the stroke of clamping sleeve 13 is -adjnstably limited by stop tube 17 a much simpler sort of gauge Z5 can be used because it is no longer necessary to limit the extent to which gripping members 4 enter therein in order always to have a constant length of lead projecting from gripping members 'KL Capt20 can also be made of transparent material and provided with la cylindrical cavity 22 having an opening 24 into which a piece of lead may be inserted to show the color and hardness of the lead being used in the pen- Plug-23 seals olf cavit 22 from tube 3 and also secures the latter to cap 20.

What I claim is:

A draftsmans lead dropping pencil comprising a lead containing tube having lead gripping members with exterior cam faces thereon at the `drawing end of the pencil, a pencil body coaxially mounted about said tube, said body being in threaded engagement with said tube whereby said body is adjustable axially relative to said tube, a clamping sleeve coaxially mounted around said tube between the latter and said body, said sleeve being axially slideable relative to both said tube and said body and having one end engaging said cam faces, a stop ring on the tube, a compressible helical spring mounted around said tube and `acting axially between it and the other end of said sleeve to exert pressure therebetween and contacting the clamping sleeve and the stop ring, whereby said sleeve engages said cam faces to grip .the lead in said tube, a stop positioned between said tube and said body and secured to the latter and spaced axially from said other end of said sleeve, said space being adjustable by means of said threaded engagement of said tube and said body, whereby pressure axially upon said sleeve in a direction toward the other end of the pencil and simultaneously pressure axially by the draftsmans lingers upon said body without movement ofthe fingers therefrom in the opposite direction moves said sleeve axially through said space to disengage said sleeve from said cam `faces and release the lead in said tube, `and said body being provided with axially parallel ridges spaced about the inner surface thereof and axially slideable in corresponding grooves provided in said sleeve, whereby rotation of the latter relative to said body is prevented.

References Cited in the le of this patent UNITED STATES PATENTS 235,149 Hoffman Dec. 7, 1880 1,296,900 Zimdors Mar. 11, 1919 2,038,248 Steuer Apr. 21,1936 2,491,061 Savoie Dec. 13, 1949 2,512,273 Harvey June 20, 1950 FOREIGN PATENTS 15,187 Great'Britain Dec. l0, 1885 373,458 Great Britain May 26, 1932 378,703 Great Britain Aug. 18, 1932 176,245 Switzerland June 17, 1935 964,731 France Aug. 23, 1950 

